Analysis And Research On Filtering Characteristics Of Two-dimensional Photonic Crystal Defect Structures

Photonic crystal is one of the latest research directions in the field of optical communication.Because of its own photonic bandgap and photon local area of these two important characteristics,its own can be used as a natural band-stop filter.In addition,photonic crystal fiber large angle transition,photonic crystal logic gate integration and other advantages are the future development advantages of optical communication.Typical photonic crystal filters include wavelength division multiplexers in the field of optical communications,signal uploaders,etc.,and various filters based on the unique properties of photonic crystals are being developed quickly.According to the excellent characteristics of photonic crystals,the use of photonic crystal material made of the filter will make the widely used optical fiber communication transmission efficiency greatly improved.Based on the current application of photonic crystal and the important position of the filter in the communication system,this paper studies the theoretical analysis methods commonly used in several photonic crystals based on the related concepts and characteristics of photonic crystals.The main factors influencing the band structure of two-dimensional photonic crystal are analyzed,and the bandgap structure of photonic crystal is simulated by Rsoft software.On the basis of this,the transmission characteristics of different structure photonic crystal filters are studied,and a new photonic crystal filter structure is designed.And the optimal design and simulation analysis of the proposed filter structure is carried out to improve the transmission efficiency of the filter.In order to improve the performance of photonic crystal filters,and promote the development of optical communications.The main contents of the thesis include the following aspects:1、The basic situation of the current communication field is analyzed,the development direction and requirements of the future optical communication are studied,and the photonic crystal is selected as the research object.The research status of photonic crystals at home and abroad,the concept and classification of photonic crystals,the two important characteristics of photonic crystals and the main applications of photonic crystals are analyzed.2、The general theory of photonic crystal is analyzed,and the principal equation is obtained by deriving the main analytical method-plane wave expansion method,finite time domain difference method and mixed variational method.3、Based on the plane wave expansion method,the three main influencing factors of the two-dimensional photonic crystal band structure are studied in detail: the cell structure of the photonic crystal,the relative refractive index of the dielectric material and the dielectric filling rate of the dielectric material,and the modeling and simulation analysis of each factor.4、Four basic waveguide and resonator coupling systems are analyzed.The single-loop double-waveguide structure is deeply analyzed,and the structure is optimized by changing the parameters,so that the transmission efficiency is improved remarkably.A new photonic crystal filter structure is proposed.By changing its structure parameters,the filter is optimized to improve the transmission efficiency and make the lossless propagation.In order to make the proposed new structure more practical,a new structure based on the four-channel filter structure.Through the simulation of the structure,it is concluded that the structure can be adjusted by changing the internal parameters,which greatly increases the value of the device in the field of optical communication.After simulation verification,the four-channel filter structure of the transmission efficiency can be as high as 90%,showing a superior optical characteristics.Through the research of this paper,it can be shown that photonic crystal is a design and manufacturing material of excellent optical device,and has great research potential,which can play an important role in integrating optical path,optical logic gate and optical signal processing device.At the same time,the use of photonic crystals for the design of optical devices remains to be further studied.